When some elk amble across U.S. Highway 101 here on the Olympic Peninsula of western Washington, radio collars around their necks set off flashing lights up and down the busy road.
Across the continent, when moose wander out on State Highway 4 in the mountains of western Maine, their hulking bodies break an infrared beam that triggers flashing lights on moose warning signs.
On re-engineered highways between the broadcasting elk and the beam-breaking moose, there are underpasses for tortoises in California, vibration-detectors for deer in Wyoming and a 52-foot-wide overpass for deer, foxes, coyotes and opossums on Interstate Highway 75 in Florida.
At an accelerating pace, federal and state highways across much of the United States are being fitted with critter-crossing technology. It is an attempt to halt a rising tide of human death and roadkill, the grisly result of more cars, more sprawl and a resurgence of large hoofed animals, including deer, elk and, deadliest of all, moose.